Stockholders' Equity - Additional Information (Detail) - USD ($)							1 Months Ended	12 Months Ended
	Nov. 27, 2019	Aug. 19, 2019	May 08, 2019	Apr. 11, 2019	Apr. 03, 2018	Oct. 20, 2017	May 08, 2019	Dec. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Consideration from sale of stock							$ 18,300,000
Deferred financing costs								$ 88,000	$ 200,000
Common Stock
Class of Stock [Line Items]
Common stock shares issued (in shares)									10,000,000
Price of stock sold (in USD per share)	$ 1.45
Consideration from sale of stock	$ 3,100,000
Offering expense, accrued								100,000
Registered Direct Offering
Class of Stock [Line Items]
Net proceeds from issuance of common stock								$ 3,162,000	$ 0
Registered Direct Offering | Common Stock
Class of Stock [Line Items]
Common stock shares issued (in shares)	2,181,034							2,181,034
At-The-Market Offering
Class of Stock [Line Items]
Price of stock sold (in USD per share)								$ 1.57
Consideration from sale of stock								$ 5,200,000
Offering expense, accrued								$ 100,000
Maximum aggregate offering price (up to)		$ 15,000,000.0
Commissions on proceeds from the sale of shares		3.00%
Shares issued in transaction (in shares)								3,599,141
Commissions and other offering expenses								$ 200,000
Net proceeds from issuance of common stock								$ 5,289,000	0
At-The-Market Offering | Common Stock
Class of Stock [Line Items]
Common stock shares issued (in shares)								3,599,141
Public Stock Offering
Class of Stock [Line Items]
Price of stock sold (in USD per share)				$ 3.29
Shares issued in transaction (in shares)				5,000,000
Net proceeds from issuance of common stock								$ 18,331,000	$ 45,604,000
Public Stock Offering | Common Stock
Class of Stock [Line Items]
Common stock shares issued (in shares)								5,750,000
Over-Allotment
Class of Stock [Line Items]
Price of stock sold (in USD per share)			$ 3.29				$ 3.29
Shares issued in transaction (in shares)			750,000
IPO
Class of Stock [Line Items]
Common stock shares issued (in shares)					10,000,000
Offering price (in USD per share)					$ 5.00
Net proceeds from issuance of common stock					$ 45,600,000
Equity Lines of Credit | Lincoln Park Capital Fund Llc
Class of Stock [Line Items]
Common stock shares issued (in shares)						11,375
Value of shares obligated to purchase, next thirty months (up to)						$ 35,000,000
Fair value of share						$ 15.30
Affiliate Of One Of Company's Directors | Affiliated Entity | Registered Direct Offering | Common Stock
Class of Stock [Line Items]
Common stock shares issued (in shares)	689,655
Affiliate Of One Of Company's Directors | Affiliated Entity | Public Stock Offering
Class of Stock [Line Items]
Shares issued in transaction (in shares)				528,571